1. Drug Sample Information
In this experiment, FRINGE desktop X-ray diffractometer was used to analyze the diffraction of montmorillonite powder produced by a company.
2. Drug Pretreatment Steps
(1) Weigh approximately 4g of montmorillonite powder, add 50ml of water, stir, filter, dry the filter residue at 105°C, then grind into fine powder and sieve through 200-mesh.
(2) Take a suitable amount of the processed montmorillonite sample from step (1). Place it on a sample holder. Then put the holder into a desiccator. The desiccator contains a saturated sodium chloride solution. The relative humidity is about 75% at 20°C. Keep it in the desiccator for about 12 hours.
(3) Flatten the sample on the holder from step (2). Perform the measurement according to the X-ray diffraction method. Refer to General Rule 0451 (Powder X-ray Diffraction Method).
3. Test parameter setting
| Instrument model: FRINGE | 【Full Spectrum Scan Settings】 | 【Local Scan Settings】 |
| Target：Cu | Angle range：2-80° | Angle range：15-35° |
| Pipe pressure：40kV | Step width:0.05°/step | Step width:0.02°/step |
| Pipe flow：40mA | Test time：0.6s/step | Test time：1.2s/step |
4. Analysis results
(1) Identification of Montmorillonite
| Compare the characteristic peaks of montmorillonite in the map | 5.8° | 19.8° | 61.8° |
| Montmorillonite powder | 5.8562° | 19.8224° | 61.8800° |
Montmorillonite scattering characteristic peak display map
【Conclusion】
Montmorillonite Powder Identification: The X-ray powder diffraction pattern of the test sample shall match the characteristic peaks of montmorillonite reference material [diffraction angles (2θ) approximately 5.8°, 19.8°, and 61.8°].
Analysis of the drug's diffraction pattern revealed peaks at 5.8562°, 19.8224°, and 61.8800°, demonstrating essential consistency with the characteristic peaks of montmorillonite.
(2) Cristobalite and Other Impurities Identification
Local diffraction map of montmorillonite scattering (unbuckled background)
Partial X-ray Diffraction Pattern of Montmorillonite Powder (Without Background Subtraction)
【Result Determination】
Cristobalite and Other Impurities:
Measure the peak-to-baseline heights of the montmorillonite characteristic peak (2θ ≈ 19.8°), cristobalite diffraction peak (2θ ≈ 22.0°), and other impurity diffraction peaks. Calculate the ratio of each peak height relative to the montmorillonite characteristic peak height. In the X-ray powder diffraction pattern of the test sample:
-The peak height ratio of the cristobalite diffraction peak shall not exceed 50%.
-The peak height ratio of any other single impurity diffraction peak shall not exceed 70%.
Through analysis of the 15-35° diffraction pattern of montmorillonite powder, the following characteristic peaks are observed:
-Montmorillonite characteristic peak at 19.80° with a peak height of 1581
-Quartz characteristic peak at 26.64° with a peak height of 408
The quartz/montmorillonite peak height ratio is calculated as: 25.81% < 70%.
The impurity peak/montmorillonite peak height ratios at 2θ=17.84° and 29.94° are 11.0% and 11.64% respectively, both less than 70%.
These results indicate that the drug's impurity control meets the standard.